MAGNETRON AND MANUFACTURING METHOD THEREFOR

PROBLEM TO BE SOLVED: To enhance manufacturability of a pole piece.SOLUTION: A magnetron includes a positive electrode cylinder 1, a vane 2, a negative electrode 5 and pole pieces 8, 9. The positive electrode cylinder 1 has both open ends. The vane 2 is in contact with the inner surface of the positive electrode cylinder 1, and extends toward the axis 41 of the positive electrode cylinder. The negative electrode 5 extends along the central axis 41. The pole pieces 8, 9 are annular ferromagnetic bodies arranged at both end openings of the positive electrode cylinder 1. The pole pieces 8, 9 are formed by superposing a plurality of plates. Respective plates 81, 82, 91, 92 composing the pole pieces 8, 9 are formed by punching a plate of ferromagnetic body by means of a press.